Mentalization refers to the capacity to form mental representations of intentional mental states (e.g. emotions, needs, desires, beliefs, purposes) and thereby to be aware of and understand these mental states in oneself and in others. It helps individuals to sustain psychological balance and flexibly manage different kinds of life’s challenges. A well-functioning capacity for mentalization is a key factor in mental health and enables individuals to navigate their social environment. This article illustrates the central concepts of mentalizing, and the session material of clinical case shows how mentalization-based treatment (MBT) fosters and strengthens mentalizing capacity in practice. It highlights the methods and processes of mentalization-based therapy through a detailed, session-based case example, presented as a pedagogical case study designed to make the clinical practice of MBT visible.